Myoclonic Seizure Disorder

Introduction

Myoclonic Seizure disorder is a type of seizure condition where patients experience sudden brief duration movements of the limbs, body, head & neck areas in various combinations. These movements appear like sudden jerking movements, as if somebody was hit by electrical shock.

Myoclonic movements of muscles can take pace in the absence of seizures or epilepsies. For example hypnic-jerk, a type of myclonic jerk occur as some people fall to sleep. People get myoclonus of the diaphragm muscle and produces the familiar condition called as hiccups. These are generally normal myoclonic conditions and are not epileptic or seizure in nature.

Myoclonus can originate due to pathologies in the spinal cord or brainstem and while these conditions are abnormal but they are not epileptic in nature since they are not arising from the brain cortex, and also EEG comes normal.

The seizure /epilepsy related myoclonus occurs in the following settings

PME (progressive myoclonic epilepsy) syndromes:

These occur during child hood and adolescent age (sometimes late), and as the name implies these conditions are progressive in nature (degenerative neurological diseases). Along with myoclonus patients also generally experience other types of epileptic seizures. Along with different kinds of seizures cognitive decline too occurs. The important examples include;

• Lafora body type
• Unverricht-Lundborg disease
• MERRF syndrome (myoclonic epilepsy and ragged red fiber syndrome) – a mitochondrial disorder
• NCL (neuronal ceroid lipofuscinosis)
• Mucolipidoses type 1 (sialidosis) etc

JME:

A type of hereditary epilepsy disorder of idiopathic type presents with myoclous, generalized tonic clonic seizures and petit mal seizures.

Lennox Gastatut syndrome:

A type of symptomatic epilepsy disorder presenting with various types of epileptic seizures along with mental retardation.

A varieties of cortical or systemic pathologies can irriate the cortical neurons and trigger myoclonic type seizures and examples include;

• Infections: TORCH, encephalitis etc
• CJD (creutzfeldt Jacob Disease)
• Ischemic (stroke)
• Head injuries
• Anoxic encephalopathy secondary to cardiac arrest etc
• Medication side effects
• Toxin exposure
• Uremia (kidney failure)
• Liver failure etc

Diagnosis

Epileptic myoclonic-seizures may be picked up on an EEG. Polyspikes are characteristic EEG finding for this type of seizure. If a structural cause of brain is suspected them a CT or MRI of the brain is ordered. A bunch of blood tests (and sometimes cerebrospinal fluid as well) depending upon what we suspect. Genetic & biopsy tests may be necessary too.

Treatment

The following AED (antiepileptic drugs) are usually employed for the control of these seizures;

• Klonopin (Clonazepam)
• Depakote (Sodium Valproate)
• Lamictal (Lamotrigine)
• Topamax (Topiramate)
• Zonegran (Zonisamide) etc.

Familiar AEDs like phenytoin, carbamazepine etc are not useful and sometimes even worsen these kinds of seizures.

The primary pathologies are treated independently.

A neurologist is frequently involved in the management of myoclonic seizure disorder.



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